Chapter-1005: The first time we see Marco since chapter 1000 i.e. when he sent Zoro to the rooftop:
^Marco lands on the floor due to King's attack. There is no sign of Queen near them, and he looks slightly bruised in the top-left panel of page two.
Chapter-1006: Marco attacks Queen and reminds him that he is supposed to be fighting him.
^Bottom-left: Marco has more bruises than chapter 1005 meaning it's from his battle with King.
Also chapter-1006, but after fighting King and Queen
^^Marco looked no different from when he first attacked Queen on the page above. He looks just as exhausted and equally bruised. Also, Marco says it's pretty tough to fight them both at the same time, which if we're to be exact, translates to "It's hard to fight them at the same time i.e. it's hard to keep up with the two without getting beaten, not that his HP reduced from 70 to 50. Sanji apparently says the same thing about them in this chapter and I doubt he fought them for more than a minute.
So while it's true Marco must have lost a bit of his stamina from the 2 on 1 fight, the major chunk of his stamina is actually spent on King and in fighting the Ice Oni transformation.